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"Multivariate graphics"

Simon Schwab, Ruth Harbord, Valerio Zerbi, Lloyd Elliott, Soroosh Afyouni, Jim Q Smith, Mark W Woolrich, Stephen M Smith, Thomas E Nichols
There are a growing number of neuroimaging methods that model spatio-temporal patterns of brain activity to allow more meaningful characterizations of brain networks. This paper proposes dynamic graphical models (DGMs) for dynamic, directed functional connectivity. DGMs are a multivariate graphical model with time-varying coefficients that describe instantaneous directed relationships between nodes. A further benefit of DGMs is that networks may contain loops and that large networks can be estimated. We use network simulations and human resting-state fMRI (N = 500) to investigate the validity and reliability of the estimated networks...
July 15, 2018: NeuroImage
E M E Ayala, M A Aragón
Here, we show the effects of sexual steroids, progesterone, testosterone, or estradiol on motility parameters of boar sperm. Sixteen commercial seminal doses, four each of four adult boars, were analyzed using computer assisted sperm analysis (CASA). Mean values of motility parameters were analyzed by bivariate and multivariate statistics. Principal component analysis (PCA), followed by hierarchical clustering, was applied on data of motility parameters, provided automatically as intervals by the CASA system...
November 2017: Cytometry. Part A: the Journal of the International Society for Analytical Cytology
Eunho Yang, Pradeep Ravikumar, Genevera I Allen, Zhandong Liu
Undirected graphical models, or Markov networks, are a popular class of statistical models, used in a wide variety of applications. Popular instances of this class include Gaussian graphical models and Ising models. In many settings, however, it might not be clear which subclass of graphical models to use, particularly for non-Gaussian and non-categorical data. In this paper, we consider a general sub-class of graphical models where the node-wise conditional distributions arise from exponential families. This allows us to derive multivariate graphical model distributions from univariate exponential family distributions, such as the Poisson, negative binomial, and exponential distributions...
December 2015: Journal of Machine Learning Research: JMLR
David I Inouye, Pradeep Ravikumar, Inderjit S Dhillon
We develop Square Root Graphical Models (SQR), a novel class of parametric graphical models that provides multivariate generalizations of univariate exponential family distributions. Previous multivariate graphical models (Yang et al., 2015) did not allow positive dependencies for the exponential and Poisson generalizations. However, in many real-world datasets, variables clearly have positive dependencies. For example, the airport delay time in New York-modeled as an exponential distribution-is positively related to the delay time in Boston...
June 2016: JMLR Workshop and Conference Proceedings
Luis Becerril Martínez, Rubén Huerta Crispín, Maximino Méndez Mendoza, Oswaldo Hernández Gallegos, Andrés Aragón Martínez
In order to identify unreliable data in a dataset of motility parameters obtained from a pilot study acquired by a veterinarian with experience in boar semen handling, but without experience in the operation of a computer assisted sperm analysis (CASA) system, a multivariate graphical and statistical analysis was performed. Sixteen boar semen samples were aliquoted then incubated with varying concentrations of progesterone from 0 to 3.33 µg/ml and analyzed in a CASA system. After standardization of the data, Chernoff faces were pictured for each measurement, and a principal component analysis (PCA) was used to reduce the dimensionality and pre-process the data before hierarchical clustering...
June 2013: Systems Biology in Reproductive Medicine
Peter H Van Ness, Terrence E Murphy, Katy L B Araujo, Margaret A Pisani
OBJECTIVE: Graphical methods for generating explanatory hypotheses from limited categorical data are described and illustrated. STUDY DESIGN AND SETTING: Univariate, bivariate, multivariate, and multiplicative graphical methods were applied to clinical data regarding very ill older persons. The data to which these methods were applied were limited as to their nature (e.g., nominal categorical data) or quality (e.g., data subject to measurement error and missing values)...
February 2012: Journal of Clinical Epidemiology
Nadia Sourial, Christina Wolfson, Bin Zhu, Jacqueline Quail, John Fletcher, Sathya Karunananthan, Karen Bandeen-Roche, François Béland, Howard Bergman
OBJECTIVE: Correspondence analysis (CA) is a multivariate graphical technique designed to explore the relationships among categorical variables. Epidemiologists frequently collect data on multiple categorical variables with the goal of examining associations among these variables. Nevertheless, CA appears to be an underused technique in epidemiology. The objective of this article is to present the utility of CA in an epidemiological context. STUDY DESIGN AND SETTING: The theory and interpretation of CA in the case of two and more than two variables are illustrated through two examples...
June 2010: Journal of Clinical Epidemiology
B L K Chawes, E Kreiner-Møller, H Bisgaard
BACKGROUND: Allergic and nonallergic rhinitis are common childhood disorders. OBJECTIVE: To study nasal eosinophilia and nasal airway patency in young children with allergic and nonallergic rhinitis to assess the pathology behind such diagnoses. METHODS: We investigated 255 children at six years of age from the Copenhagen Prospective Study on Asthma in Childhood birth cohort assessing rhinitis history, specific immunoglobulin E relevant to rhinitis symptoms, nasal eosinophilia and nasal airway patency by acoustic rhinometry before and after decongestion...
October 2009: Allergy
Eve Syrkin Wurtele, Jie Li, Lixia Diao, Hailong Zhang, Carol M Foster, Beth Fatland, Julie Dickerson, Andrew Brown, Zach Cox, Dianne Cook, Eun-Kyung Lee, Heike Hofmann
MetNet ( approximately mash/metnetex/metabolicnetex.html) is publicly available software in development for analysis of genome-wide RNA, protein and metabolite profiling data. The software is designed to enable the biologist to visualize, statistically analyse and model a metabolic and regulatory network map of Arabidopsis, combined with gene expression profiling data. It contains a JAVA interface to an interactions database (MetNetDB) containing information on regulatory and metabolic interactions derived from a combination of web databases (TAIR, KEGG, BRENDA) and input from biologists in their area of expertise...
2003: Comparative and Functional Genomics
D H Schwela, G H Krause
To evaluate the effects of dry and wet deposition on forest trees (Picea abies [L.] Karst.), the LIS-Essen is operating an Open-Top Chamber Field Station within an area where novel forest decline has been prevalent since 1982. Chambers are ventilated with either ambient or charcoal-filtered air and receive either natural or artificial rain, the latter being prepared by natural rain and distilled water in ratio 1:10. Besides deposition data, acquired above and below the tree crowns as well as via lysimeters of soil percolates, various parameters describing vitality of trees are measured...
1989: Environmental Pollution
J E Dumas, P Lemay, J P Dauwalder
Describes the application of a new analytical approach (derived from synergetics, a complex dynamic systems theory) to home observational data of mother-child interactions in average dyads and dyads with children referred for disruptive behavior problems at home and school (n = 11 in each group). Results show that (1) the two groups differed in their daily interactions in predictable ways, and (2) the most frequent patterns of interactions observed in the two groups brought them back repeatedly to behave in similar ways toward each other...
August 2001: Journal of Abnormal Child Psychology
Loslever, Barbier
This paper describes a procedure to determine the progress of the gait rehabilitation in relation to a reference obtained from a normal population. This procedure includes three stages: (1) data standardization, to give time and space aspects comparable from one individual to another; (2) monovariate and multivariate distance computation, to assess the difference between a disabled patient at a given time in the rehabilitation and the reference computed from individuals with a 'normal' gait; and (3) distance evolution...
January 1, 1998: Gait & Posture
L M Jørgensen, T I Sørensen, M Schroll, S Larsen
The aim of the present study was to analyse the influence of dietary factors on weight change in a multifactorial context by use of graphical models. A random sample of 2304 Danish men and women, aged 30, 40, 50, and 60 years, living in Copenhagen County underwent a general health examination, and their BMI was calculated. They all completed questionnaires regarding education, life conditions, life habits, and dietary intake at entry. At follow-up five years later BMI was also calculated. BMI at entry depended on family predisposition to obesity, and for women, on cohabitation as well...
March 3, 1997: Ugeskrift for Laeger
L M Jørgensen, T I Sørensen, M Schroll, S Larsen
OBJECTIVE: To analyse the influence of dietary factors on weight changes in a multifactorial context by use of graphical models. DESIGN: Two age-stratified cohorts of Danish men and women were examined twice with five years interval. SETTING: The Glostrup Population Studies in the Copenhagen County, Denmark. SUBJECTS: A random population sample of 2009 men and women, aged 30, 40, 50, and 60 years. METHODS: At baseline all underwent a general health examination including measurement of height and weight, and they completed questionnaires regarding familial predisposition, cohabitation, school education, vocational training, social class, smoking habits, physical activity during work and leisure time, and parity...
December 1995: International Journal of Obesity and related Metabolic Disorders
M García-Bonafé, A Moragas, I de Torres, M Sans
Differentiation between renal oncocytomas and well-differentiated oxyphilic cell renal carcinomas from fine needle aspiration cytology smears may present considerable difficulties. To better define diagnostic criteria, we used high-resolution architectural characteristics of nucleus and cytoplasm based on mathematical morphologic concepts. Particulate structural elements were selected for their size and optical density by the so-called top-hat function. Spatial density, size distribution and a function of distance between particles were computed...
June 1993: Analytical and Quantitative Cytology and Histology
C Ceccarelli, D Santini, P Chieco, M Taffurelli, D Marrano, A M Mancini
BACKGROUND: Commonly used clinical and morphologic criteria have been reported to be of limited value in predicting the outcome of malignant tumours of the breast. Integrated information from the quantitative analysis in tumour tissue of biological parameters such as oestrogen and progesterone receptors (ER and PGR), proliferative activity, and proto-oncogene p53, c-erB2, and bcl-2 expression, may be useful for defining the biology of growth of breast carcinoma and to plan effective therapeutic strategies...
March 1995: Annals of Oncology: Official Journal of the European Society for Medical Oncology
A N Wilton, C C Laurie-Ahlberg, T H Emigh, J W Curtsinger
This report describes an investigation of the specificities of the genetic effects, caused by whole chromosome substitution, on the activities of 23 enzymes in Drosophila melanogaster. Two types of correlation estimates are examined, the product-moment correlation over the chromosome substitution line means and the corresponding correlation of line effects, which is a standardized covariance component estimate. The two types of correlations give very similar results. Although there is ample evidence for specific line effects on individual enzyme activities, there are extensive intercorrelations among many of the enzymes for both second- and third-chromosome substitution lines...
October 1982: Genetics
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